Short answer: the Pressure Systems Safety Regulations 2000 cover systems at work that hold steam, or a gas or liquefied gas above 0.5 bar (including hot water kept above its boiling point), such as steam boilers, air receivers and refrigeration plant whose compressor motors total more than 25 kW. The user must set safe operating limits, hold a written scheme of examination drawn up or certified by a competent person, have examinations done to it and keep the system maintained. Maintenance and examination are separate jobs.
Is it a pressure system?
The Pressure Systems Safety Regulations 2000 (PSSR) apply to "pressure systems which are used or intended to be used at work" (reg 3(2)). A pressure system is a system of one or more rigid pressure vessels with their pipework and protective devices, or certain pipework and pipelines, "which contains or is liable to contain a relevant fluid" (reg 2(1)). A relevant fluid is:
- steam;
- a gas, or a liquid that would have a vapour pressure above 0.5 bar at its actual temperature or at 17.5 °C, at a pressure greater than 0.5 bar above atmospheric;
- a gas dissolved under pressure in a solvent in a porous substance, which is acetylene.
HSE's summary puts it as: steam at any pressure, compressed or liquefied gas including air above 0.5 bar, and "pressurised hot water above 110 °C". Hydraulic oil systems are not covered. The water in low temperature hot water heating, running below its boiling point, is not a relevant fluid. The gas cushion in a pre-charged expansion vessel on a sealed system is a compressed gas, so the user should decide with a competent person whether those vessels form a pressure system; each one under 250 bar litres falls within the partial exception below.
Schedule 1 lists 25 complete exceptions and 3 partial ones. Three matter most in plant rooms:
- Refrigeration up to 25 kW: "any vapour compression refrigeration system incorporating compressor drive motors, including standby compressor motors, having a total installed power not exceeding 25 kW" is outside PSSR (Sch 1 Part I, para 18).
- Pipelines at low pressure: a pipeline in which the pressure does not exceed 2 bar is outside PSSR (Sch 1 Part I, para 5). Pipelines cross the boundaries of premises; pipework inside a plant room is not a pipeline.
- Small vessels: regulations 5(4), 8 to 10 and 14 (marking, the written scheme, examination and records) do not apply to a system holding a relevant fluid other than steam "if the product of the pressure in bar and internal volume in litres of its pressure vessels is in each case less than 250 bar litres" (Sch 1 Part II, para 2). There is no such exception for steam: "where the relevant fluid is steam all the regulations apply, irrespective of the vessel pressure and size" (L122, para 213).
| Item | Written scheme of examination? | Basis |
|---|---|---|
| Steam boiler with its pipework and protective devices | Likely to need one | INDG178; L122 para 113 |
| Compressed air receiver at or above 250 bar litres | Likely to need one | INDG178 |
| Compressed air receiver below 250 bar litres | Not needed; other duties such as maintenance still apply | Sch 1 Part II, para 2 |
| Vapour compression refrigeration over 25 kW installed power | Likely to need one | INDG178; L122 para 113 |
| Vapour compression refrigeration up to 25 kW | No: outside PSSR | Sch 1 Part I, para 18 |
| Fixed LPG storage supplying fuel for heating in a workplace | Likely to need one | INDG178; L122 para 113 |
| Gas-loaded hydraulic accumulator, if part of a pressure system | Likely to need one | L122 para 113 |
| Office hot water urn | Unlikely | INDG178; L122 para 113 |
| Low temperature hot water heating below boiling point | No relevant fluid in the water; check any gas-charged expansion vessels separately | Reg 2(1); L122 paras 19 and 21 |
HSE stresses that these are examples: "You must decide whether your pressurised system is covered by the Regulations in practice." L122 says the user or owner "should decide, in consultation with a person competent to advise as appropriate, whether a written scheme of examination is required" (para 113). For hot water storage, see our guide to calorifier maintenance.
What PSSR asks, regulation by regulation
| Regulation | Duty | On whom |
|---|---|---|
| 7 | Do not operate the system until its safe operating limits are established | User of an installed system |
| 8 | Hold a written scheme for periodic examination of all protective devices, every pressure vessel in which a defect may give rise to danger, and the parts of pipework where a defect may give rise to danger; the scheme must be drawn up or certified by a competent person and reviewed at appropriate intervals | User |
| 9 | Have the parts in the scheme examined by a competent person within the intervals in the scheme; the competent person sends a signed, dated report within 28 days, or before the date in the report if sooner | User; competent person |
| 10 | If an examination finds imminent danger, the competent person reports it at once, the system is not operated until put right, and the enforcing authority gets a report within 14 days | Competent person; user |
| 11 | Provide adequate and suitable instructions for safe operation and for emergencies, and operate only in line with them | User |
| 12 | Keep the system "properly maintained in good repair, so as to prevent danger" | User |
| 13 | Make sure nothing about a modification or repair "gives rise to danger or otherwise impairs the operation of any protective device or inspection facility" | Employer of the person doing the modification or repair |
| 5(2) | Provide written information about a modification or repair, given to the user immediately after it | Employer of the person doing the modification or repair |
| 14 | Keep the last examination report, earlier reports that help judge safety, the manufacturer's instructions supplied under the Pressure Equipment (Safety) Regulations 2016, and any postponement agreement, at the premises | User |
Maintenance is not examination
L122 is direct about this: "The need for maintenance should not be confused with the requirement for examinations under the written scheme. They are two separate issues although problems identified during an examination under the written scheme may require maintenance to correct" (para 163). HSE's introduction to pressure equipment adds that a statutory examination "is not a substitute for regular and routine maintenance".
L122 says a maintenance programme should take account of the age of the system, operating conditions, working environment, the manufacturer's or supplier's instructions, previous maintenance history, the competent person's examination reports, other inspections, repairs or modifications, and the risks from failure (para 165). Where the manufacturer has provided maintenance instructions, "these should form the basis of the maintenance programme" (para 167). It also gives a plant room example: "recurrent discharge of a relief valve may indicate that the system or the relief valve are not working correctly and should be investigated as part of the planned maintenance regime" (para 166).
For a maintenance contractor that means:
- Service to the manufacturer's instructions and the site's programme, and read the latest examination report before the visit so that any repairs it calls for are in the plan.
- Make sure nothing about a repair or modification gives rise to danger or impairs a protective device or inspection facility: regulation 13 puts that duty on your firm as the employer of the person doing the work. Do not change a safety valve setting, remove a protective device or alter the system without the user's agreement, as the change may need the competent person to review the written scheme (reg 8(2)(b)).
- After a repair or modification, give the user written information about it straight away (reg 5(2) and 5(3)(c)). The user may need the competent person to look at it before use.
- Know the date in the latest report after which the system may not be operated without a further examination (reg 9(5)(c)). The user can postpone it once, by written agreement with the competent person and notice to the enforcing authority before the date (reg 9(7)).
Worked example: a leisure centre plant room
A maintenance contractor looks after the plant room of a leisure centre. It holds a 270-litre air receiver for pneumatic valves and a 24-litre receiver on a small workshop compressor, each with its safety valve set at 8 bar, a chiller whose compressor motors total 30 kW installed power, and two low temperature hot water boilers on a sealed system.
For the bar-litre sum, do not use the gauge reading on the day. L122 says that where pressure varies, "the maximum pressure that is normally reached should be the determining factor" (para 19). Using the safety valve setting, which is at or above that, keeps the sum on the safe side; if the result is close to 250, ask the competent person. For a chiller, the 25 kW test is the installed power of the compressor motors, not the cooling output on the nameplate.
| Item | Working | Written scheme? |
|---|---|---|
| 270-litre receiver, safety valve at 8 bar | 8 × 270 = 2,160 bar litres, at or above 250 | Yes |
| 24-litre receiver, safety valve at 8 bar | 8 × 24 = 192 bar litres, below 250 | No; other duties, such as regs 7, 11, 12 and 13, still apply |
| Chiller, compressor motors 30 kW in total | Over the 25 kW refrigeration exception | Likely, as HSE's examples show |
| Low temperature hot water boilers | Water below its boiling point is not a relevant fluid | No for the water; the expansion vessels' gas side is decided separately, and each is likely under 250 bar litres |
The centre's operator, as user, holds the written scheme for the large receiver and the chiller, drawn up by a competent person who carries out the examinations. The contractor's quarterly visit services the receivers, compressors and chiller to the manufacturer's instructions, records pressures against the safe operating limits and notes any relief valve discharge for investigation. The chiller's refrigerant work is done by an engineer with the right F-gas category, under a company certificate. The contractor records the next examination date from the latest report on its own job record, so a postponement or a missed examination is visible to the office.
Who does what
- The user (the employer or self-employed person in control of operating an installed system) sets the safe operating limits, holds the written scheme, arranges examinations, provides operating instructions, keeps the system maintained and keeps the records.
- The competent person draws up or certifies the written scheme, examines the system, reports within 28 days and acts on imminent danger. Regulation 2 defines a competent person as an individual other than an employee, or a body. HSE says an in-house competent person should be independent from the operating functions and able to stop the equipment.
- The maintenance contractor maintains the system to the programme, repairs without impairing protective devices (reg 13), and gives the user written information after any repair or modification.
- A firm that supplies an installed system by lease or hire can agree in writing to take on the user's duties for the written scheme, examinations, operating instructions, maintenance and records (Schedule 2, para 1). While that agreement is in force, the supplier carries those duties.
What to record
- Each pressure system item: description, location, serial number, and its safe operating limits
- Whether it is in the written scheme, the date of the last examination and the date after which it may not be operated without another
- On each visit: pressures and temperatures against the limits, protective device checks done to the manufacturer's instructions, leaks found
- Repairs and modifications, with the written information given to the user and when
- Any relief valve discharge, and what was found when it was investigated
- Engineer, date and signature
Running pressure plant visits in Field Suite
- Equipment register: each receiver, boiler and chiller at its site with make, model, serial number, service interval and job history, and a QR label on the plant that opens its page.
- Contracts: visits that repeat every set number of months, each with a form attached, created as jobs a set number of days before they are due.
- Your own form: build a checklist with the form builder, with number questions for pressures, Pass/Fail questions for each protective device check, and date questions for the last and next examination.
- Faults: a passing safety valve becomes a fault marked by urgency, and the office turns it into a quote.
See planned maintenance software and pump maintenance software, read about booster set servicing and its diaphragm vessels, use our pump service checklist, or book a demo.
Field Suite is job management software. The written scheme of examination, the competent person and the manufacturer's instructions decide how pressure plant is examined and maintained.
Questions
Can our own engineer be the competent person?
Not as an individual employee. Regulation 2 defines a competent person as an individual other than an employee, or a body, which acts through its employees. L122 says the expertise can lie within the user's own organisation, in which case the user is acting as competent person, and that in-house staff should have a suitable degree of independence from the operating functions (paras 30 and 33). HSE adds that they must have authority to stop the equipment. A maintenance contractor's engineer servicing the plant is not the competent person for its examinations. L122 paragraphs 28 to 34 and 100 to 102 cover the role.
Does servicing count as the statutory examination?
No. HSE says examination under the written scheme is not a substitute for routine maintenance, and the reverse is also true: they are separate duties under regulations 9 and 12.
Can an examination date be moved?
Once per examination, by written agreement between the user and the competent person, if it does not give rise to danger, and with written notice to the enforcing authority before the date (reg 9(7)).
Where must the records be kept?
For an installed system, at the premises where it is installed, or at other premises approved by the enforcing authority (reg 14(2)).
Sources
- Pressure Systems Safety Regulations 2000, regulation 2 (interpretation). https://www.legislation.gov.uk/uksi/2000/128/regulation/2
- Pressure Systems Safety Regulations 2000, regulation 3 (application and duties). https://www.legislation.gov.uk/uksi/2000/128/regulation/3
- Pressure Systems Safety Regulations 2000, regulation 5 (provision of information and marking). https://www.legislation.gov.uk/uksi/2000/128/regulation/5
- Pressure Systems Safety Regulations 2000, regulation 7 (safe operating limits). https://www.legislation.gov.uk/uksi/2000/128/regulation/7
- Pressure Systems Safety Regulations 2000, regulation 8 (written scheme of examination). https://www.legislation.gov.uk/uksi/2000/128/regulation/8
- Pressure Systems Safety Regulations 2000, regulation 9 (examination in accordance with the written scheme). https://www.legislation.gov.uk/uksi/2000/128/regulation/9
- Pressure Systems Safety Regulations 2000, regulation 10 (action in case of imminent danger). https://www.legislation.gov.uk/uksi/2000/128/regulation/10
- Pressure Systems Safety Regulations 2000, regulation 11 (operation). https://www.legislation.gov.uk/uksi/2000/128/regulation/11
- Pressure Systems Safety Regulations 2000, regulation 12 (maintenance). https://www.legislation.gov.uk/uksi/2000/128/regulation/12
- Pressure Systems Safety Regulations 2000, regulation 13 (modification and repair). https://www.legislation.gov.uk/uksi/2000/128/regulation/13
- Pressure Systems Safety Regulations 2000, regulation 14 (keeping of records). https://www.legislation.gov.uk/uksi/2000/128/regulation/14
- Pressure Systems Safety Regulations 2000, Schedule 1 (exceptions). https://www.legislation.gov.uk/uksi/2000/128/schedule/1
- Pressure Systems Safety Regulations 2000, Schedule 2 (systems supplied by lease, hire or other arrangements). https://www.legislation.gov.uk/uksi/2000/128/schedule/2
- HSE, Pressure Systems Safety Regulations 2000 (PSSR). https://www.hse.gov.uk/pressure-systems/pssr.htm
- HSE, Introduction to pressure equipment. https://www.hse.gov.uk/pressure-systems/about.htm
- HSE, Written schemes of examination, INDG178(rev2). https://www.hse.gov.uk/pubns/indg178.pdf
- HSE, Safety of pressure systems, Approved Code of Practice L122 (second edition, 2014), paras 19, 113, 163 to 167 and 213. https://www.hse.gov.uk/pubns/priced/l122.pdf
Last checked: 5 November 2026 against the sources above.
Checked in detail: PSSR 2000 regs 2, 3, 5, 7 to 14 and Schedules 1 and 2 on legislation.gov.uk (no outstanding effects); HSE PSSR and pressure equipment pages; HSE INDG178(rev2); HSE L122 (2014) paras 19 to 21, 28 to 34, 100 to 102, 113, 163 to 167 and 213.
Field Suite is job management software for UK building services firms, not a consultancy. Your own risk assessments, contracts and advisers decide what applies to your work. Spotted a mistake? Email info@fieldsuiteapp.com and we correct it.